Light beams or optical signals are frequently used to transmit digital data, for example, in fiber optic systems for long-distance telephony and internet communication. Additionally, much research has been done regarding the use of optical signals to transmit data between electronic components on circuit boards.
Consequently, optical technology plays a significant role in modern telecommunications and data communication. Examples of optical components used in such systems include optical or light sources such as light emitting diodes and lasers, waveguides, fiber optics, lenses and other optics, photo-detectors and other optical sensors, optically-sensitive semiconductors, optical modulators, and others.
Systems making use of optical components often rely upon the precise manipulation of optical energy, such as a beam of light, to accomplish a desired task. This is especially true in systems utilizing light for high-speed, low-energy communication between two nodes. Often optical resonators are used to selectively filter, switch, or modulate light beams.
Ring resonators are a type of optical resonator. Ring resonators typically have an optical waveguide in a closed loop coupled to a tangential waveguide. Ring resonators also have a characteristic resonant frequency, which can be controlled by selective tuning in some systems.
When light of the appropriate wavelength is introduced into the loop by the tangential waveguide, the light beam builds up in intensity over multiple round-trips through the closed loop due to constructive interference. Alternatively, light of a wavelength apart from the resonant frequency or range of the ring resonator is attenuated by destructive interference in the ring resonator. The resonant optical energy then exits the loop back into the tangential waveguide.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.